Changeset 87822ce in mainline for uspace/app/top

Timestamp:

2021-03-04T19:14:30Z (5 years ago)

Author:

Jiri Svoboda <jiri@…>

Branches:

lfn, master, serial, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export

Children:

d6c4d40

Parents:

760a392

Message:

Avoid infinite loop when console communication is broken

Need to make sure callers of console_get_event_timeout() can distinguish
between timeout and I/O error. Fix all callers of console_get_event()
and console_get_event_timeout() not to enter infinite loop when console
connection is broken. Also avoid setting of errno variable.

Location:

uspace/app/top

Files:

• screen.c (modified) (4 diffs)
• screen.h (modified) (2 diffs)
• top.c (modified) (3 diffs)

uspace/app/top/screen.c

@@ -534 +534 @@
 /** Get char with timeout
  *
+ * @param sec Timeout in seconds
+ * @param rch Place to store character on success
+ * @return EOK on success, ETIMEOUT on time out, EIO on other error
  */
-int tgetchar(sec_t sec)
-{
+errno_t tgetchar(sec_t sec, int *rch)
+{
+        errno_t rc;
+
         /*
          * Reset timeleft whenever it is not positive.
@@ -548 +553 @@
          * update timeleft so that the next call to tgetchar()
          * will not wait as long. If there is no input,
-         * make timeleft zero and return -1.
+         * make timeleft zero and return ETIMEOUT.
          */
 
@@ -557 +562 @@
 
                 warning_timeleft -= timeleft;
-                if (!console_get_event_timeout(console, &event, &timeleft)) {
+                rc = console_get_event_timeout(console, &event, &timeleft);
+                if (rc == ETIMEOUT) {
                         timeleft = 0;
-                        return -1;
-                }
+                        return ETIMEOUT;
+                }
+
+                if (rc != EOK)
+                        return EIO;
+
                 warning_timeleft += timeleft;
 
@@ -567 +577 @@
         }
 
-        return (int) c;
+        *rch = (int) c;
+        return EOK;
 }
 

uspace/app/top/screen.h

@@ -35 +35 @@
 #define TOP_SCREEN_H_
 
+#include <errno.h>
 #include <io/console.h>
 #include <io/verify.h>
@@ -47 +48 @@
     _HELENOS_PRINTF_ATTRIBUTE(1, 2);
 
-extern int tgetchar(sec_t);
+extern errno_t tgetchar(sec_t, int *);
 
 #endif

uspace/app/top/top.c

@@ -583 +583 @@
         data_t data_prev;
         const char *ret = NULL;
+        errno_t rc;
+        int c;
 
         screen_init();
@@ -595 +597 @@
         /* And paint screen until death */
         while (true) {
-                int c = tgetchar(UPDATE_INTERVAL);
-
-                if (c < 0) { /* timeout */
+                rc = tgetchar(UPDATE_INTERVAL, &c);
+
+                if (rc == ETIMEOUT) { /* timeout */
                         data_prev = data;
                         if ((ret = read_data(&data)) != NULL) {
@@ -608 +610 @@
 
                         c = -1;
+                } else if (rc != EOK) {
+                        /* Error (e.g. communication with console lost) */
+                        goto out;
                 }